Welcome to the forums, andrew5.
I'm not quite sure what you mean.. the attachment icon is there as a choice, obviously, to provide a quick way for you to insert a pic or whatever.. do you want that choice to not be there and only be in the menu?
The only way to accomplish that, I think, is to root your Desire and then find a ROM which has that feature.
Perhaps others will chime in.. but let me know if I'm off track on what you meant by your question.